Make the given changes in the indicated examples of this section and then solve the resulting problems.

In Example 5, change “pure methanol” to “of a blend with 50.0% methanol.”

Data from Example 5

A refinery has 7250 L of a gasoline-methanol blend that is 6.00% methanol. How much pure methanol must be added so that the resulting blend is 10.0% methanol? 

First, let x = the number of liters of methanol to be added. The total volume of methanol in the final blend is the volume in the original blend plus that which is added. This total volume is to be 10.0% of the final blend. See Fig. 1.21.

0.0600(7250) + x = 0.100(7250 + x)

435 + x = 725 + 0.100x

0.900x = 290, x = 322L to be added.

Checking (to three significant digits), there would be 757 L of methanol of a total 7570 L.